Dorset was sent to Sidney, Iowa, in 1897 to administer doses of the old bacterial vaccine against hog cholera. The trial was a complete failure. Dorset and de Schweinitz studied the problem of hog cholera in early 1904, finding that the disease could be transmitted by bacteria-free filtrates of sera from infected animals, thus proving a viral etiology of the disease and implying the bacilli found by Salmon and Smith were pathogenic secondary invaders.

While conducting experiments in Iowa in 1903, Dorset's team of researchers determined that blood from immune hogs gave only temporary immunity to susceptible hogs. However, the immune sera could be combined with a second injection of a live virus.

At the 1901 meeting of the SAB, Dorset presented on a "Variety of the Hog Cholera Bacillus which Closely Resembles Bacillus typhosus." He noted that this organism fermented glucose without the evolution of gas, and as such was culturally closer to B. typhosus than to the hog cholera group of bacteria. Still, the "author concludes that when the source and pathogenic properties of this variety are considered, it should be classed among the hog cholera bacteria." BACT NOM Also at the 1901 meeting of the SAB, de Schweinitz and Dorset submitted, but did not present, a paper on "Some Considerations in Regard to the Relations between Hog Cholera, Colon and Typhoid Bacilli." BACT NOM

At the same 1901 meeting, Dorset also presented a "Note on Branched Forms of Tubercle Bacilli Found in Cultures," (which was discussed by Moore, Novy and Sedgwick) and at the 1902 meeting he summarized his paper from American Medicine (5 April 1902) in which he described an "Egg Medium for the Cultivation of Tubercle Bacilli." De Schweinitz and Dorset also presented "A Preliminary Chemical Study of Various Tubercle Bacilli," which was discussed by Abbott, Welch and Bergey. At the 1904 meeting of the SAB, Dorset and Emery submitted some "Notes on the Chemical Constitution of Bacillus tuberculosis," which was read by Emery. Dorset did not present again at the SAB, until reappearing in 1911 as the supervisor of the session on "Human and Animal Pathologic Bacteriology."

Discovered the commercially viable serum for hog cholera control in 1907, developed a method of culturing viruses in eggs, and developed many of the early techniques of modern virology. Dorset's egg medium was a real innovation, used in a variety of pure culture contexts, including tuberculosis.

Dorset also produced a synthetic medium for the growth of tubercle bacilli, more efficient than Koch's broth that increased the production of tuberculin.

Dorset was rarely active in the AVMA, presenting a paper on hog cholera in 1927.